[PATCH AUTOSEL 4.14 087/105] EDAC: Fix global-out-of-bounds write when setting edac_mc_poll_msec

Sasha Levin
2019-07-15T14:34:07Z

From: Eiichi Tsukata <devel@etsukata.com>

[ Upstream commit d8655e7630dafa88bc37f101640e39c736399771 ]

Commit 9da21b1509d8 ("EDAC: Poll timeout cannot be zero, p2") assumes
edac_mc_poll_msec to be unsigned long, but the type of the variable still
remained as int. Setting edac_mc_poll_msec can trigger out-of-bounds
write.

Reproducer:

# echo 1001 > /sys/module/edac_core/parameters/edac_mc_poll_msec

KASAN report:

BUG: KASAN: global-out-of-bounds in edac_set_poll_msec+0x140/0x150
Write of size 8 at addr ffffffffb91b2d00 by task bash/1996

CPU: 1 PID: 1996 Comm: bash Not tainted 5.2.0-rc6+ #23
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
Call Trace:
dump_stack+0xca/0x13e
print_address_description.cold+0x5/0x246
__kasan_report.cold+0x75/0x9a
? edac_set_poll_msec+0x140/0x150
kasan_report+0xe/0x20
edac_set_poll_msec+0x140/0x150
? dimmdev_location_show+0x30/0x30
? vfs_lock_file+0xe0/0xe0
? _raw_spin_lock+0x87/0xe0
param_attr_store+0x1b5/0x310
? param_array_set+0x4f0/0x4f0
module_attr_store+0x58/0x80
? module_attr_show+0x80/0x80
sysfs_kf_write+0x13d/0x1a0
kernfs_fop_write+0x2bc/0x460
? sysfs_kf_bin_read+0x270/0x270
? kernfs_notify+0x1f0/0x1f0
__vfs_write+0x81/0x100
vfs_write+0x1e1/0x560
ksys_write+0x126/0x250
? __ia32_sys_read+0xb0/0xb0
? do_syscall_64+0x1f/0x390
do_syscall_64+0xc1/0x390
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fa7caa5e970
Code: 73 01 c3 48 8b 0d 28 d5 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 99 2d 2c 00 00 75 10 b8 01 00 00 00 04
RSP: 002b:00007fff6acfdfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fa7caa5e970
RDX: 0000000000000005 RSI: 0000000000e95c08 RDI: 0000000000000001
RBP: 0000000000e95c08 R08: 00007fa7cad1e760 R09: 00007fa7cb36a700
R10: 0000000000000073 R11: 0000000000000246 R12: 0000000000000005
R13: 0000000000000001 R14: 00007fa7cad1d600 R15: 0000000000000005

The buggy address belongs to the variable:
edac_mc_poll_msec+0x0/0x40

Memory state around the buggy address:
ffffffffb91b2c00: 00 00 00 00 fa fa fa fa 00 00 00 00 fa fa fa fa
ffffffffb91b2c80: 00 00 00 00 fa fa fa fa 00 00 00 00 fa fa fa fa
>ffffffffb91b2d00: 04 fa fa fa fa fa fa fa 04 fa fa fa fa fa fa fa
^
ffffffffb91b2d80: 04 fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
ffffffffb91b2e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Fix it by changing the type of edac_mc_poll_msec to unsigned int.
The reason why this patch adopts unsigned int rather than unsigned long
is msecs_to_jiffies() assumes arg to be unsigned int. We can avoid
integer conversion bugs and unsigned int will be large enough for
edac_mc_poll_msec.

Reviewed-by: James Morse <james.morse@arm.com>
Fixes: 9da21b1509d8 ("EDAC: Poll timeout cannot be zero, p2")
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/edac/edac_mc_sysfs.c | 16 ++++++++--------
drivers/edac/edac_module.h | 2 +-
2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 148c4649b155..a4acfa81dfe0 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -26,7 +26,7 @@
static int edac_mc_log_ue = 1;
static int edac_mc_log_ce = 1;
static int edac_mc_panic_on_ue;
-static int edac_mc_poll_msec = 1000;
+static unsigned int edac_mc_poll_msec = 1000;

/* Getter functions for above */
int edac_mc_get_log_ue(void)
@@ -45,30 +45,30 @@ int edac_mc_get_panic_on_ue(void)
}

/* this is temporary */
-int edac_mc_get_poll_msec(void)
+unsigned int edac_mc_get_poll_msec(void)
{
return edac_mc_poll_msec;
}

static int edac_set_poll_msec(const char *val, struct kernel_param *kp)
{
- unsigned long l;
+ unsigned int i;
int ret;

if (!val)
return -EINVAL;

- ret = kstrtoul(val, 0, &l);
+ ret = kstrtouint(val, 0, &i);
if (ret)
return ret;

- if (l < 1000)
+ if (i < 1000)
return -EINVAL;

- *((unsigned long *)kp->arg) = l;
+ *((unsigned int *)kp->arg) = i;

/* notify edac_mc engine to reset the poll period */
- edac_mc_reset_delay_period(l);
+ edac_mc_reset_delay_period(i);

return 0;
}
@@ -82,7 +82,7 @@ MODULE_PARM_DESC(edac_mc_log_ue,
module_param(edac_mc_log_ce, int, 0644);
MODULE_PARM_DESC(edac_mc_log_ce,
"Log correctable error to console: 0=off 1=on");
-module_param_call(edac_mc_poll_msec, edac_set_poll_msec, param_get_int,
+module_param_call(edac_mc_poll_msec, edac_set_poll_msec, param_get_uint,
&edac_mc_poll_msec, 0644);
MODULE_PARM_DESC(edac_mc_poll_msec, "Polling period in milliseconds");

diff --git a/drivers/edac/edac_module.h b/drivers/edac/edac_module.h
index dec88dcea036..c9f0e73872a6 100644
--- a/drivers/edac/edac_module.h
+++ b/drivers/edac/edac_module.h
@@ -36,7 +36,7 @@ extern int edac_mc_get_log_ue(void);
extern int edac_mc_get_log_ce(void);
extern int edac_mc_get_panic_on_ue(void);
extern int edac_get_poll_msec(void);
-extern int edac_mc_get_poll_msec(void);
+extern unsigned int edac_mc_get_poll_msec(void);

unsigned edac_dimm_info_location(struct dimm_info *dimm, char *buf,
unsigned len);
--
2.20.1